Langdon's Critique of the Aquatic Ape Hypothesis

Algis V. Kuliukas M.Sc. Perth, WA, Australia Abstract A challenge to Langdon’s 1997 critique of the Aquatic Ape Hypothesis has still not been published despite the paper appearing to have a number of weaknesses which deserve a response. Langdon’s analysis of “anatomical evidence for the AAH” seems to have been directed against an interpreted hypothesis of thoroughly aquatic human ancestors and not towards Alister Hardy’s (1960) original hypothesis that humans were merely “more-aquatic in the past”. Therefore the critique was often superficial and largely based on false comparisons with truly aquatic mammals. Several of the arguments used to discredit the AAH’s claim for greater parsimony were flawed. And criticism of the lack of fossil evidence for an ‘aquatic phase’ was based largely upon a single proponent’s view. Six years on, significant new evidence has emerged and other AAH-based models have been published which demand that the debate be reopened. It is argued that the notion that water has acted as some kind of agent of selection throughout human evolution has, in fact, not yet been refuted and deserves more serious consideration than it has hitherto received. Introduction “Overall, it will be clear that I do not think it would be correct to designate our early hominid ancestors as ‘aquatic’. But at the same time there does seem to be evidence that not only did they take to the water from time to time but that the water (and by this I mean inland lakes and rivers) was a habitat that provided enough extra food to count as an agency for selection.” Vernon Reynolds (in Cold and Watery? Hot and Dusty? Our Ancestral Environment and Our Ancestors Themselves: An Overview. In Roede et al 1991 p 340. That paragraph, taken from the concluding editorial section of the Valkenberg symposium (Roede et al 1991), which specifically considered the Aquatic Ape Hypothesis, signals a clear message that the hypothesis, although probably wrong in its extreme (and, perhaps, originally interpreted) form, does deserve consideration in some revised, moderate reconstruction. That water might have acted as an agent of selection in human evolution has, however, remained more the target of ridicule than research in the field of paleoanthropology. This state of affairs has remained to this day, at least in part, because of the critique of the ‘Aquatic Ape Hypothesis’ (AAH) by Langdon (1997) which continues to be the only paper to be published in a scientific journal to have considered it, and rejected it. Langdon (1997:p480) justified writing his critique by arguing “the aquatic ape hypothesis continues to be encountered by puzzled students who wonder why mainstream paleoanthropologists overlook it. If only because of this last audience, it should not be ignored.” Langdon makes a good point. Students and lay people who hear about the theory for the first time tend to be open to it. ‘That makes sense’ is a common reaction. Indeed, bearing this in mind, the whisperingly negative reaction to the Aquatic Ape Hypothesis from probably the great majority of professional paleoanthropologists is, perhaps, as interesting as the hypothesis itself. It has been the subject of at least two PhD theses to the knowledge of the author and warranted Graham Richards to write a whole chapter on the subject entitled “The Refutation that Never Was: The Reception of the Aquatic Ape Theory, 1972-1987” (Richards 1991) although Langdon makes no mention of this angle on the subject in his critique. Whatever the reasons for the lack of serious attention afforded the AAH by paleoanthropologists in the past, be they some kind of “perceived ‘outsidership’ of Elaine Morgan”, as argued by Richards (1991:p124), or simply bad timing, arguing for the importance of water in 1960 when everyone else was sure it was due to aridity, Langdon was right to address the issue. The interest by new students in the aquatic ape theory is as real today as it was in 1997. However, a student of human evolution familiar with the literature today might be forgiven for concluding that Langdon’s critique was the last word on the subject, its final refutation, considering that no reply has been published since. It is with that audience in mind that this riposte has been written: The weaknesses in Langdon’s paper deserve to be 1 of 15 26/10/2011 12:18 μμ challenged, pro-AAH arguments not covered should be heard and an altered version of the AAH, modified to reflect Langdon’s and others’ criticisms, should be aired for public scrutiny. It also aims to respond to a recent, plea from Phillip V. Tobias “to re-examine these claims, much as Langdon (1997) has done” (Tobias 2002:p16). Tobias has been a lone voice in the field of paleoanthropology, in the past few years, calling for his peers to reconsider the role that water has played in human evolution (Tobias 1998a). The document will mirror the structure of Langdon’s original paper, critiquing his arguments but, additionally outlining some AAH-related ideas which were not covered in the paper and suggesting a new redefinition of the hypothesis. The aquatic ape hypothesis (AAH)… Then Langdon introduced the hypothesis thus: “The AAH in its present form was first articulated by Alister Hardy in 1960 in an issue of New Scientist magazine featuring the relationship of man and the sea, past present and future.” Although the phrase ‘in its present form’ is probably out of date six years on, it is true that most proponents of some kind of AAH take Hardy’s (1960) paper as their starting point. It should be noted however, that the AAH, like any model of human evolution, is under constant revision in response to criticisms and as new evidence emerges. Therefore its present form today is not the same as the one Langdon dismissed in 1997. Some of those new forms will be discussed later in this document. One small but important point about Hardy’s original paper, overlooked by Langdon, was its rather modest title: 'Was man more aquatic in the past?' (my emphasis). Here lies one of the most common misunderstandings of the hypothesis. On first hearing the term ‘aquatic ape hypothesis’, reviewers could be forgiven for understanding that this was an hypothesis which actually postulated that humans evolved from a truly aquatic ape, in the sense that seals are aquatic mammals, although this is clearly not the case. Hardy (1960), Morgan (1972, 1982, 1990, 1994, 1998), Cunnane (1980), Crawford & Marsh (1989), Verhaegen (1990, 1993, 1994), Knight (1991), Evans (1992), Ellis (1993), Verhaegen et al. (2000, 2001), Kuliukas (2002) and other proponents have never made such claims. They have only argued that some human traits may be better explained as adaptations to life by the water’s edge than alternative explanations hitherto understood. The key part to understand in Hardy’s title and his thesis, then, is the word ‘more’. The meaning of the AAH should merely taken to be the hypothesis that human evolution underwent a phase or phases where our ancestors were merely more aquatic than humans are today and also, by implication, more aquatic than our ape cousins’ ancestors were, and whose extant survivors are today. Langdon did no justice to the hypothesis by avoiding this complexity and merely defining it’s meaning as “having observed a number of anatomical parallels between distinctively human traits and marine animals, he [Hardy] proposed that the human lineage had been shaped evolutionarily by a temporary phase of adaptation to a littoral habitat” (1997:p480). Later in the paper Langdon (1997:p490) accuses Morgan of making false comparisons in positing the AAH in opposition to “the savannah theory”. He states (1997:p490): “The savannah hypothesis that Morgan criticizes turns out to be a straw man”, arguing that many in the field “are now discarding the savannah setting for hominid divergence.” This may, or may not be correct. Many paleoanthropologists have published work (e.g. Rodman & McHenry 1980, Lovejoy 1981, Wheeler 1984, 1991, 1992, Vrba 1985, Hunt 1994) before Langdon’s critique (and many before Morgan’s latest books) which are very much based on the model that aridity and a greater adaptation to more open and grassy habitats was a significant driver of hominid evolution. Indeed Tobias is quite open about agreeing with Morgan on this point. He wrote “Until recently, the evolution of early hominids in the savannah has been a strongly held, prevailing hypothesis” (Tobias 2002:p15) and “the competing [with the AAH] hypothesis is no longer tenable since I presented much evidence against it in my Daryll Forde Lecture at University College London in 1995” (Tobias 2002:p16). It does appear to be the case that since Langdon’s critique fewer papers have been published arguing for a savannah setting for hominid evolution than before, but the general assumption still remains that it was the aridification of Africa since the Miocene that was the main contemporaneous ecological change going on and that a general move to more open habitats was the resulting factor that drove the process of hominization. (See, e.g., Leonard 2003.) However, whether the savannah theory is ‘dead’ or not, anyone accusing the AAH of using ‘straw man’ arguments should be very careful not to be found guilty of doing the same thing themselves in trying to discredit it. By emphasising comparisons with fully aquatic marine mammals and avoiding areas of discussion which invoke human ancestors as being merely more exposed to water as an agent of selection than our ape cousins Langdon, and other ‘aquaskeptics,’ are open to accusations of using the same straw man tactics themselves.

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